1. Field of the Invention
This invention relates to motion picture projectors and in particular to a film tension absorbing system to absorb high film tension shock within the projector.
2. Description of the Prior Art
When loading a roll of film into a motion picture projector, the film strip is normally threaded through a particular film path including a number of toothed sprockets, through a film shuttle, and, in the case of a projector provided with a audio amplifier, around a sound drum. The leading end of the film strip then is wrapped about a takeup reel upon which it is wound during projection.
In practice, during this threading operation a slack portion of the film strip develops between the supply reel and the first drive sprocket and between the takeup reel and the takeup sprocket. When starting the projector, these slack portions are quickly wound on the takeup reel and into the projector by the drive sprocket causing a jerk or snapping of the film strip. This high film tension shock has often been found to cause damage to the perforations of the film strip over a period of time.
In early projectors no means was provided on the projector to accommodate for this high film tension usually generated during start-up of the machine. Some attempts have been made to provide a snubbing effect by utilizing a biased tooth ring portion on the sprocket wheel to accommodate for a small amount of relative movement between the film strip and the sprocket wheel. However, both of these previous attempts have not been completely satisfactory.